Optimization of alkaline protease production by Streptomyces sp. strain isolated from saltpan environment

Microbial proteases: ubiquitous enzymes with innumerable uses

Proteases are ubiquitous enzymes, having significant physiological roles in both synthesis and degradation. The use of microbial proteases in food fermentation is an age-old process, which is today being successfully employed in other industries with the advent of ‘omics’ era and innovations in genetic and protein engineering approaches. Proteases have found application in industries besides food, like leather, textiles, detergent, waste management, agriculture, animal husbandry, cosmetics, and pharmaceutics. With the rising demands and applications, researchers are exploring various approaches to discover, redesign, or artificially synthesize enzymes with better applicability in the industrial processes. These enzymes offer a sustainable and environmentally safer option, besides possessing economic and commercial value. Various bacterial and fungal proteases are already holding a commercially pivotal role in the industry. The current review summarizes the characteristics and types of proteases, microbial source, their current and prospective applications in various industries, and future challenges. Promoting these biocatalysts will prove significant in betterment of the modern world.

A dual-functional aminopeptidase from Streptomyces canus T20 and its application in the preparation of small rice peptides

An aminopeptidase that derived from Streptomyces canus T20 (ScAP) was successfully expressed and characterized in Escherichia coli BL21 (DE3) for first time. The specific activity was 6000 U/mg, which is highest in Streptomyces aminopeptidases. Its optimal conditions were 60 °C and pH 8.0, respectively. ScAP exhibited excellent thermal and alkaline pH stability, retained 80.0% maximal activity at 50 °C for 200 h or at pH 9.0 for 24 h. Its activity observed to be complete inhibited by 0.1 mM EDTA and enhanced by Ca²⁺ and Co²⁺ to 115.4% and 104.0% respectively. ScAP also has exhibited high specificity towards rice protein on preparation of small peptides. The yield of small rice peptides achieved 66.5%, which is highest by far. Besides, ScAP have significant debittering effect on rice peptides. Results showed that bitter intensity score decreased by 49.0% with optimum condition (0.048% ScAP at 50 °C for 6 h). Therefore, ScAP as dual functional aminopeptidase of hydrolytic and debittering might have a potential application in the production of high yield and low bitterness of small rice peptides.